Evaluation of Trend in Rainfall: A Case Study of Dharmapuri District, Tamilnadu, India Balathandayutham K.1,*, Kottiswaran S.V.2, Valliammai A.3 1Department of Agronomy, PAJANCOA & RI, Karaikal 2Department of Soil and Water Conservation Engineering, AEC &RI, Coimbatore 3Water technology Centre, TNAU, Coimbatore, Tamilnadu, India *Email: balathandayutham03@gmail.com
Online published on 23 December, 2016. Abstract Rainfall, its pattern and its analysis is of interest to many researchers. This study aims to determine rainfall trends in the annual and seasonal total rainfall over Dharmapuri districtof Tamilnadu using34 years (1980–2013) monthly rainfall data at ten rain gauge stations. Analysis of rainfall using nonparametric Mann-Kendall (MK) tests, Sen's slope estimator and parametric test of linear regression test a at the 5% significant level. The results showed that increasing and decreasing tends were found for annual and seasonal rainfall over the period of 1980–2013. These events are strong indication of climate change in the district. The Mann-Kendall statistic Z = 0.4553, Sen's slope estimate Q = 9.08, and the regression slope coefficient a = 9.13 indicate a positive trend for Dharmapuri station in annual rainfall. The maximum reduction of rainfall was found for Thopiyar dam for the Man-Kendall statistic Z =-3.187, Sen's slope estimate Q =-20.98, and the regression slope coefficient a =-15.11 indicate a negative trend of annual and seasonal rainfall. The presence of trend in annual and seasonal rainfall series determined by Mann-Kendall Z statistics and Sen's Slope estimator reflected in the linear regression analysis. Top Keywords Rainfall, Sen's slope estimator, Trend, Regression. Top |